I'm developing an android application.I have a problem to send a message to the telegram contact list of the user of my application when they install it on their devices. What can I do? How can I use form service of telegram just for this problem in my app. is there any sample ?
Telegram does not allow bots to send messages to the users that haven't started a conversation with the bot before. You should recommend the users in the contact list to add your bot to their chats by clicking just once on your bot's start button. (For example, you can forward a post from your own bot that contains its link and then ask the user to tap the /start button or simply send it as a command to bot.)
Simply, telegram bots are different from systems like Email starting a conversation is a one-way process. But right after the conversation began, it changes to a two-way conversation.